Machine for drilling holes in hard materials



A. MIEVILLE 3,105,482 MACHINE FVOR DRILLING HOLES in HARD MATERIALS Oct;1, 1963 Filed Sept. 26 1961 9 Sheets-Sheet 1 FIG. 7

Oct. 1, 1963 A. MlEVlLLE 3,105,432

MACHINE FOR DRILLING HOLES IN HARD MATERI AL S Filed Sept. 26. 1961 9Sheets-Sheet 2 Oct. 1, 1963 A. MIEVILLE 3.105.482

MACHINE FOR DRILLING HOLES IN HARD MATERIALS Filed Sept. 26. 1961 9 shets-sh e s Oct. 1, 1963 A. MlEVlLLE 3,105,482

MACHINE FOR DRILLING HOLES IN HARD MATERIALS Filed Sept. 26. 1961 9Sheets-Sheet 4 Oct. 1, 1963 A. MlEVlLLE 3,105,482

MACHINE FOR DRILLING HOLES IN HARD MATERIALS Filed Sept. 26, 1961 9Sheets-Sheet s Oct. 1, 1963 A. MIIEVILLE MACHINE FOR DRILLING HOLES INHARD MATERIALS 9 Sheets-Sheet 6 Filed Sept. 26. 1961 A. MlEVlLLE3,105,482

MACHINE FOR DRILLING HOLES IN HARD MATERIALS Oct. 1, 1963 9 Sheets-Sheet7 Filed Sept. 26. 1961 Oct. 1, 1963 A. MIEVILLE 3,105,482

MACHINE FOR DRILLING HOLES IN HARD MATERIALS Filed Sept. 26. 1961 9Sheets-Sheet 8 Oct. 1, 1963 A. MIEVILLE 3, 0

MACHINE FOR DRILLING HOLES IN HARD MATERIALS Filed Sept. 26. 1961 9Sheets-Sheet 9 United States Patent 3,165,482 MACHINE FOR DRILLING RULESIN HARD MATERIALS Andr Mieville, Lausanne, Switzerland, assignor toMarie-Louise Spirit-Klein, Geneva, Switzerland Filed Sept. 26, 1961,Ser. No. 149,938 3 Claims. (til. 12530) The present invention relates toa machine for making holes in hard materials, more particularly hardmetals, ceramic materials, industrial stones, stones for dies, or stonesfor timepieces. This machine comprises a drillsupporting spindlesubjected to the action of electromagnetic means which impart to thespindle a vibratory axial movement superimposed on the rotary movementof the spindle.

The machine according to this invention is characterised in that thespindle rotates in bearings with air bushes.

Embodiments of the invention chosen by way of example are illustrated inthe accompanying drawings, in which:

FIGURES 1 and 2 are respectively an elevation and a plan view of a firstembodiment;

FIGURES 3 and 4 are views in section on lines Ill-J11 and IV-IV of IGURE2;

FIGURE 5 is a view in cross-section, at the level of line VV of FIGURE3,

FIGURE 6 is a view in elevation, and partly in section, of a secondembodiment;

FIGURE 7 is a view, partly in section, corresponding to FIGURE 4,

FIGURE 8 is a View in section on line VTIIV'III of FIGURE 7(corresponding to FIGURE 5 of the first embodiment),

FIGURE 9 is a diagram of the electrical system of the first embodiment,

FIGURE 10 is a modification of this circuit,

FIGURE 11 is the electrical system of the second embodiment, and

FIGURES 12 to 16 are modifications of the electrical system of thesecond embodiment.

The first embodiment, illustrated in FIGURES 1 to 5 and 9, comprises acasing in the form of a cover 29, and a cylindrical body 21 locatedwithin this cover and closed at both ends by two caps 22 and 23. Thedrillsupporting spindle 24 rotates in two air-bush bearings 25 and 26mounted respectively in the body 21 and in the lower cap 23. In itscentral port-ion the spindle 24 carries a rotor 27 of a three-phasehigh-frequency motor of which the stator 23 is accommodated in anannular chamber 29 :of the body 21. A channel 30 is provided throughwhich wires, not shown, lead to the stator, and to a six-pole connector31 to which these wires are also connected.

The motor enables the spindle to be rotated at speeds of the order of60,000 to 120,600 revolutions per minute.

The bearings are of the kind having chambers 32 (FIGURE 5) and mesupplied with compressed air through an opening 33 and a duct 34 leadingto the centers of the two bearings.

At the top end of the spindle 24 is disposed a conical nipple 35engaging in a recess of corresponding shape in a tubular member 36screwed into the cap 22. This member constitutes the core of anelectromagnet of which the winding 37 is accommodated in the upper partof the body 21.

The distance of axial movement of the spindle 24 is limited at thebottom by the bearing 25 and at the top by the bearing 25. This distancecan be accurately adjusted by axially displacing the bearing 26 by meansof an eccentric device 38.

3-,ld5,482 Patented Get. 1, 1963 The inner cylindrical tip 38a of device38 is slightly eccentric with its axis of symmetry displaced in relationto the axis of rotation to the axis of rotation of device 38; therefore,when device 38 is turned, the bearing 26 is shifted slightly upwards ordownwards, as required, in the axial direction of spindle 24. Three sucheccentric devices 38 are used and are disposed at an angular distance ofto ensure accurate adjustment of bearing 26 on three peripheral pointsof application.

The coil 37 is energized with a single-phase alternating current takenfrom a network to which current is supplied by an alternator; in thesystem illustrated in FIGURE 9. The coil 37 is supplied with currentthrough the connector 31 to which a plug 31a is connected and apotentiometer 42, in such a mmer that during each half- Wave the spindle24 is lifted against the action of its own Weight and then falls backunder the action of its weight,

The amplitude of this vibratory axial movement is related to the weightof the spindle and the maximum strength of the magnetic fieldv Thisamplitude is limited by the possible distance of axial movement of thespindle between the bearings 25 and 26. This amplitude may be adjustedby variably setting the potentiometer 42, and by displacing the core 35;this displacement changes the air gap and the air throttling action at40.

Some of the air driven through the bearings passes through gaps 41 and41' and escapes through a duct 39 (FIGURE 4), some of this air passesout through the bottom part of the bearing 26, and the rest passes outthrough the member 36. Some of this air thus passes through the gaps 41and '41 'Which form two air cushions that prevent the spindle fromcoming into contact with the members which limit the axial movement ofthe spindle.

Consequently, the spindle rotates and vibrates while suspended in air,and this results in minimum wear and very silent operation.

In the modification of the electrical system shown in FIGURE 10, a diode43 is provided in the circuit through which current is supplied to thecoil 37; in this way, every other half-wave is suppressed and thefrequency of the vibratory movement is halved.

The second embodiment, illustrated in FIGURES 6, 7, 8 and 11, differsfrom the first embodiment in that on the one hand the electromagnet hastwo windings 37 and 37', and on the other the bearings 25 and 26 areprovided with holes 44 (FIGURE 8).

In the second embodiment, the end of the spindle is located between thetwo windings 37 and 37 in such a manner as to be alternately attractedupwards and reelled downwards.

The winding 37 is excited by current from the network, rectified by afull-wave rectifier 45. The strength of this current can be regulated bymeans of a potentiometer 42. This strength, and the axial position ofthe member 36, are made such that the spindle maintains itself in itsupper position, against the action of its weight, when the winding 37 isexcited.

The vibratory movement is brought about by the winding 37 through whichcurrent from a source 59 passes; every other half-wave of this currentis suppressed by the diode 43. This current produces a periodic fieldopposing the field of the winding 37, which causes magnetic repulsionbetween the member 35 and the core 36 and periodical descent of thespindle. The amplitude of the current passing through the winding 37'and also the strength of the current passing through the winding 37, areregulated by means of the potentiometer 42.

The only difference between this second embodiment and the modificationthereof illustrated in FIGURE 12, is that the action of the winding 37can be regulated only by means 'of the member 36, whereas the action ofthe winding 37' can be changed by means of the potentiometer 42.

In the modification illustrated in FIGURE .13, the winding 37 isconnected directly to the source 50. An alternating current passesthrough this winding and creates a field that exerts a periodic upwardlydirected action on the spindle. The maximum strength of this field canbe adjusted by changing the axial position of the member 36. Actuallythis field is so adjusted that in the absence of current in the winding37 the spindle is raised intermittently, at the frequency of thecurrent. The winding 37' is energized with current from the source 5t)through the diode 43 which suppresses one half-wave in every two. Thestrength of this current can be adjusted by means of the potentiometer42. During each period the spindle is successively subjected to arepelling action (when both windings are excited) which displaces thespindle downwards, and to an upwardly directed action (when only thewinding 37 is excited).

In the modification illustrated in FIGURE 14, the source 59 suppliescurrent to the windings 37 and 37 in series, and these windings createfields that oppose one another. Every other half-wave is suppressed bythe diode 43, and the current can be adjusted by means of thepotentiometer 42. As a result, the spindle is subjected to anintermittent downwardly directed action. The spindle is returned to anintermediate position by the resilient cushions formed by the airescaping through the gaps 4i) and 41. This position can be adjusted byaxial displacement of the member 36.

In the modification illustrated in FIGURE 15, the source 50 suppliescurrent to the two windings in parallel. The manner of operation is thesame as described with reference to FIGURE 14.

Lastly, in the modification illustrated in FIGURE 1 the winding 37 isconnected between two phases of the high-frequency three-phase systemsupplying current to the stator coils 28. This current is rectifiedby adiode 52 and stabilised by an inductance 53. In the absence of currentin the winding 37, the current through the winding 37 produces apractically constant field which keeps the spindle in its upperposition. This action may be adjusted by axial displacement of themember 36. The Winding is energized with current by the source 51?,through the diode 43 .whch suppresses the negative halfwaves. Thepositive half-waves produce a repelling action urging the spindledownwards. This action can be adjusted by means of the potentiometer 42.

In each embodiment of the invention the drilling machine is connected tothe source 50 through a panel 51 from which the plug 31a is connected tothe drilling machine. 7

What is claimed is:

1. In a drilling machine, the combination of a drillsupporting spindle,an electric motor including a rotor rigid with the spindle and a statorsurrounding the rotor, tubular members surrounding with a slightclearance the spindle on each side of the rotor and at a small distancefrom the corresponding terminal surface of the rotor to form axialabutments for said rotor, electromagnetic means to impart to the spindleand rotor an axial reciprocating vibratory movement the amplitude ofwhich is defined by abutment of the rotor against the two tubularmembers in alternation, means feeding compressed air into the clearancesbetween the spindle and the tubular members to form air bearings forsaid spindle, said air escaping at least partly between the terminalsurfaces of the rotor and the corresponding tubular members.

2. In a drilling machine, the combination of a drillsupporting spindle,an electric motor including a rotor rigid with the spindle and a statorsurrounding the rotor, a tubular member surrounding with a slightclearance the spindle on each side of the rotor and at a small distancefrom the corresponding terminal surface of the latter to form axialabutments for said rotor, electromagnetic means adapted to impart to thespindle and rotor an axial reciprocating movement the amplitude of whichis defined by abutment of the rotor against the two tubular members inalternation, means feeding compressed air into the clearances betweenthe spindle and the tubular members to form air bearings for saidspindle, said air escaping at least partly between the terminal surfacesof the rotor and the corresponding tubular members, and hand-operablemeans controlling the axial position said one tubular member thereby toadjust the amplitude of reciprocation of the spindle.

3. In a drilling machine, the combination of a vertical drill-supportingspindle, an electric motor including a rotor rigid with the spindle anda stator surrounding the rotor, a tubular member surrounding with aslight clearance the spindle on each side of the rotor, two superposedelectromagnetic windings coaxial with the spindle and disposed above therotor, a core for the upper winding extending in vertical alignment withthe spindle at an adjustable height above the spindle, a source ofalternating current, a full-wave rectifier connected between said supplyand the upper winding, a half-wave rectifier connected between saidsupply and the lower winding to produce a periodical repulsion of thespindle downwardly against the upwardly directed attraction exertedpermanently by the upper winding, a potentiometer connected between saidhalf-wave rectifier and the lower winding, and means feeding'compressedair into the clearances between the spindle and the tubular members toform air bearings for said spindle.

References Cited in the file of this patent UNITED STATES PATENTS

1. IN A DRILLING MACHINE, THE COMBINATION OF A DRILLSUPPORTING SPINDLE, AN ELECTRIC MOTOR INCLUING A ROTOR RIGID WITH THE SPINDLE AND A STATOR SURROUNDING THE ROTOR, TUBULAR MEMBERS SURROUNDING WITH A SLIGHT CLEARANCE THE SPINDLE ON EACH SIDE OF THE ROTOR AND AT A SMALL DISTANCE FROM THE CORRESPONDING TERMINAL SURFACE OF THE ROTOR TO FORM AXIAL ABUTMENTS FOR SAID ROTOR, ELECTROMAGNETIC MEANS TO IMPART TO THE SPINDLE AND ROTOR IN AXIAL RECIPROCATING VIBRATORY MOVEMENT THE AMPLITUDE OF WHICH IS DEFINED BY ABUTMENTS OF THE ROTOR AGAINST THE TWO TUBULAR MEMBERS IN ALTERNATION, MEANS FEEDING COMPRESSED AIR INTO THE CLEARANCES BETWEEN THE SPINDLE AND THE TUBULAR MEMBERS TO FORM AIR BEARINGS FOR SAID SPINDLE, SAID AIR ESCAPING AT LEAST PARTLY BETWEEN THE TERMINAL SURFACES OF THE ROTOR AND THE CORRESPONDING TUBULAR MEMBERS. 